10 Common Poison Oak Myths

Spring in the Columbia River Gorge brings lush greens and a rainbow of wildflowers, but in this heavenly mix you will also find Toxicodendron diversilobum: Western poison oak.

If humans were as immune to the toxic oils of this plant as deer seem to be (they snack on the stuff!), we would simply admire it for the handsome foliage, and maybe even grow it in our gardens. After all, poison oak is an undeniably handsome plant… from a distance.

But instead, humans are prone to contact dermatitis when we encounter poison oak up-close, breaking out in itchy, blistering rashes that can take weeks to subside. Folklore on the cause and remedies for poison oak rash abound, and much of the information in this age of the internet is decidedly misleading.

Handsome devil: poison oak is as toxic as it is elegant.

Here are 10 common myths about poison oak — debunked — with information every hiker should know about this pesky plant:

Myth 1 – Many people are simply immune. I have hiked the poison oak-lined trails of the Columbia Gorge since the age of five, and thus have a 45-year streak of never reacting to it, despite some epic encounters. Am I immune? Maybe, but it turns out only about one-in-ten seem to have no reaction poison oak. Most of us who think we are immune have simply been careful enough — and lucky. If you have a perfect track record, assume it’s your reward for due caution, not immunity.

Myth 2 – Only the sap is toxic. Some believe it takes breaking a stem or crushing the leaves to release the toxic component of poison oak, a chemical called “urushiol” (pronounced “yoo-ROO-she-all”), and that simply brushing against it cannot transmit the toxin to your skin. In fact, urushiol is present throughout the plant, including the surface oils on the leaves and green stems of poision oak. This is especially true in spring, when new foliage literally glistens with toxic oils.

Poison oak usually looks like this in the Gorge: a spreading groundcover, 1-3 feet deep, and favoring open woods and forest margins.

Myth 3 – You’ll know you’ve got it by the next morning. While it takes only about 30 minutes for urushiol to penetrate your skin, the itchy, blistering skin reaction does not appear immediately. For most people, the symptoms are delayed at least 12 hours after exposure, and it usually takes up to 3 days for symptoms to appear — confounding hikers who think they’ve escaped a close encounter without consequence. For a first time sufferer, it generally takes even longer for the rash to appear – as much as 7 to 10 days!

Myth 4 – It takes a lot of exposure to cause a reaction. Poison oak is surprisingly toxic, and only a small amount of exposure can trigger a reaction. A single drop of urushiol on your skin contains more than enough toxin to cause a reaction, and a small amount is easily spread across your skin by perspiration or physical contact while you hike.

Myth 5 – Scratching will spread your rash. Scratching or rubbing a poison oak rash won’t make it spread to other parts of your body, assuming you’ve already washed thoroughly with soap and water. You can spread the rash if urushiol oil is still on your skin, of course. Scratching can lead to secondary skin infections, however, making your itchy misery a bit worse.

Poison oak is versatile, growing as a ground cover, shrub, or as a towering vine, as in this nightmarish scene along the McCord Creek trail.

Myth 6 – Breaking blisters will spread the rash. Breaking blisters won’t spread poison oak to other parts of your body, or other people. But open blisters can become infected and you may cause permanent scarring in the process. In very extreme cases, excessive fluid may need to be withdrawn by a doctor, though in most cases it’s best to simply let blisters heal on their own.

Myth 7 – Dead or leafless plants aren’t toxic. The bare winter stems of poison oak may look harmless, but still contain toxins. Urushiol oil has lasting power, and can stay active on any surface, including dead plants, for up to 5 years. Burning dead or dormant poison oak branches is an especially dangerous practice, as urushiol oils released in smoke can produce disastrous results, if inhaled.

Myth 8 – Dogs can’t get poison oak. Dogs are mostly protected from poison oak by their fur, though some can develop symptoms on their nose or underbelly. But all dogs can accumulate the oils on their fur, and transmit it to unwitting owners. This is especially true for off-leash dogs that might find a lush patch of poison oak just off the trail, but unseen by the dog’s owner.

The safest practice is to simply keep dogs on a leash when in poison oak country, so you know where they’ve been. Even better, give them a shampoo after the trip, as a precaution — or consider leaving Fido behind when you know you’re going to be in prolific poison oak country.

Poison oak growing in shrub form along the Rowena Plateau trail, showing the handsome bronze color of emerging leaves in spring — when the plant is especially toxic.

Myth 9 – You can develop immunity from exposure. False. With some 90% of humans allergic to urushiol, it’s only a matter of time before most of us will develop a reaction, and it turns out the more reactions you experience from exposure to urushiol, the more likely you are to react to with further exposure. But the reverse is also true: avoiding exposure (and outbreaks) reduces your susceptibility to a reaction. In other words, the myth has it backward: your best immunity comes from simply avoiding contact to begin with.

Sadly, the “develop your immunity” myth is among the more dangerous notions circulating on the internet, with countless testimonials on the “homeopathic” benefits of actually eating poison oak leaves in order to develop immunity. This is an incredibly foolhardy, dangerous idea that can lead to serious, life-threatening situations. Don’t even think about it!

Myth 10 – It’s just a rash. For most of us, this is true. But given the delayed (and varied) symptoms, poison oak reaction should always be taken seriously. As with any immune response to toxins, the symptoms can sometimes spiral out of control and become deadly. If you have a serious reaction, you need to see a doctor right away. Here are the American Academy of Dermatology guidelines for knowing if you’re having serious reaction:

• You should see a doctor if swelling persists, specially swelling that makes an eye swell shut or your face to swell.

• You should see a doctor if the rash covers a large part of your body, you have large blisters, or cannot sleep.

• If you have trouble breathing or swallowing, immediately go to an emergency room.

So, you’ve developed a rash from poison oak exposure, and it isn’t serious? Then you can treat it yourself. You can try one of these online resources for tips on managing your itchy journey ahead:

There are dozens of resources on the giving medical advice on treating poison oak rash, many with undocumented, anecdotal suggestions, so the best bet is to stick with these, or similarly respected clinical sources.

This impressive poison oak patch in the Viento area shows all three forms of the plant: groundcover, shrub and as a vine, climbing up the tree trunks.

Managing your Poison Oak exposure

The following hiking tips are adapted from recommendations by the American Academy of Dermatology and Mayo Clinic:

During your hike in poison oak country:

• If you are very sensitive, or heading into a lot of poison oak, consider one of the topical skin products containing bentoquatam, a non-prescription compound shown to protect the skin from absorbing urushiol.

• Wear long pants, long sleeves, boots, and gloves. Even when you apply a skin barrier that contains bentoquatam, you still need to cover your skin with clothing.

• Use hiking poles. They have the effect of keeping your hands up and in front of you, where you’re less likely to brush against poison oak.

• Keep your hands and arms away from your face.

• Rinse your skin right away with lukewarm water if you think you’ve been exposed. You may be able to rinse off the oil before the urushiol penetrates your skin.

Another view of an impressive patch of poison oak in the Viento area, growing in open Douglas fir forest.

After your hike in poison oak country:

• Take a shower — not a bath — with plenty of soap and lather.

• Wash all of the clothes you were wearing when you came into contact with poison oak with conventional laundry soap, set for two rinse cycles (if possible).

• Wash or wipe anything that may have urushiol oil on its surface with soap, including hiking poles, leashes, and your pet.

• Some hikers swear by Tecnu, an over-the-counter topical treatment for removing urushiol oils. Clinical tests show it to be somewhat more effective than plain soap, though neither a substitute for avoiding contact to begin with.

Learning to Recognize Poison Oak

Poison oak is easy to recognize: the old adage “leaves of three, let it be” applies, as poison oak generally has three leaflets per stem. With a bit of practice, you can learn to instantly recognize it as you hike, including the leafless stems in winter.

Here’s a close-up of the classic leaf shape (below), somewhat resembling an oak leaf, but with less pronounced lobes. In autumn, poison oak leaves take on striking hues of red and coral before dropping, leaving bare stems in winter. Note the tiny blossoms in the background — in summer, these will become clusters of greenish-white or tan berries.

Poison oak leaf detail: “Leaves of three, let it be..!”

Poison oak has several friends that it often grows with, and these plants can sometimes be confused with the real thing. They’re worth learning to identify, too, partly to know if you’ve been exposed to the real thing — but also because when you see these companion plants, you’re likely to be in poison oak habitat, and can keep an eye out for the genuine article.

One obvious example of a look-alike is the Oregon white oak (below), a classic companion of poison oak, and easily confused where brushy thickets of white oak grow in the eastern Columbia Gorge. Oak leaves are single, however, and usually larger with much deeper lobes than poison oak.

Oregon white oak can be confused with poison oak in the oak savannah country of the eastern Columbia River Gorge (courtesy PCC)

Another companion plant that is somewhat less common, but matches the “leaves of three” identifier is wild blackberry, or bramble (below). These plants are easily identified by their thorny, rambling stems that creep through the forest, small thorns on the underside of the leaves, and edible (and tasty) blackberries that form in summer.

Wild blackberry, or bramble, has “leaflets of three”, but is thorny, not smooth.

Still another companion plant that can be confused with poison oak is ocean spray, which prefers the same open woodland and forest margin habitat that poison oak enjoys. However, its leaves are single, and generally smaller than poison oak.

Ocean spray grows in dense clumps of arching stems, often reaching 8-10 feet in height. The name comes from “sprays” of hundreds of tiny, white blossoms in large clusters that cover plants in summer.

The leaves of ocean spray might initially look like poison oak, but are single and grow from a tall, arching thicket and have dramatic clusters of tiny white blossoms that give the plant its name.

Finally, snowberry is a companion plant of poison oak that normally has small, oval leaves, but in early spring grows larger, lobed leaves that can resemble poison oak at first glance. Snowberry can be identified by its thin, twiggy stems and white, inedible berries that give the plant its name. Most of its leaves are oval, and finely toothed, not lobed.

Early spring leaves on new growth are often exaggerated on snowberry, and can sometimes look like poison oak. The white berries on this plant distinguish it from the poison oak, and give the plant its name. In this view, the more typical oval leaves can bee seen in the background.

Where is Poison Oak Country?

Where can you expect to encounter poison oak? The answer is anywhere you might hike in the Gorge below an elevation of about 2,000 feet. It grows along most low-elevation trails throughout the Gorge, from Angels Rest on the west end to Dalles Mountain Ranch on the east.

Though the most prolific displays are east of Cascade Locks, you will find also lush bowers of poison oak draped over the rustic stone walls at Wahkeena Falls and Multnomah Falls, and along many sections of the popular Eagle Creek Trail (for Clackamas River hikers, it also grows in the lower canyon, under similar conditions).

Poison oak in early spring: new growth emerges in beautiful shades of copper, crimson and gold… though best appreciated from a distance!

The best bet is to assume its presence whenever hiking in the Gorge, and follow the simple precautions described in this article. It doesn’t have to ruin your hike: learning to recognize poison oak in its various forms is peace of mind, as you’ll be able to watch for it and manage your exposure with the knowledge that you know what you’re watching for.

Finally, if you’ve got small kids, there is no better way to teach them about plants than to start with identifying (and not touching!) poison oak. Print these photos of the plant (shown earlier in this article) for them to fold up and carry in a plastic sandwich bag on your next family hike:

7 Comments on “10 Common Poison Oak Myths”

Going back to some childhood haunts in the Midwest, I was taken aback at the profuse growth of poison oak in favorite hiking areas. The stuff was growing about 4 inches high through leaf mulch and kids and pets were happily running through it! I really believe that it is necessary to control this plant where the area is advertised as a recreation area. Or close it to recreation. One or the other.

In talking to a forest manager it was stated that it appears to be spreading much more with the climate warming situation.

I recently had poison oak on my forearm and I tried to get rid of it by using technu but it didn’t seem to take care of the itchiness so I thought that I might try something I had heard about but never tried . Put witch hazel on a cotton ball then rub on rash whenever it itches.